Download DYNAMIC EARTH NOTES

NOTES: ROCK CYCLE & SOIL
NOTES: PLATE TECTONICS
PLATE TECTONICS: The theory that the earth’s crust is divided into plates that move over top of the earth’s mantle.
I. CONTINENTAL DRIFT: ALFRED WEGNER - 1920’s - Did NOT explain plate motion
a. Continental Puzzle: The earth’s continents look as if they fit together like a
puzzle (ex. Africa & S. America)
b. Similar Fossils: there are fossils that have been found on different continents
during the same geologic time frame.
(Ex. A fossil that was found on both the eastern part of the US & western
Europe, but nowhere else in the world. The organism could not have traveled
from one area to the other).
c. Ancient Climates: It was determined that there were similar climates around
the same geologic time frame on two different continents that looks like they
could have fit in the same puzzle. (Ex: Coal in Antartica)
d. Similar rock types & structures: Some mountain ranges look as if they would have been a part of the same
range before the continents separated. (EX: Appalachian Mts correlate with Mt’s in Africa and Europe)
II. PLATE TECTONICS: MANY SCIENTISTS - 1960’s - EXPLAINED PLATE MOTION
a. Earthquake patterns: earthquakes tend to occur in areas along plate boundaries (Ex: The Ring of Fire)
b. Paleomagnetism: when two plates separate from each other,
especially along the ocean floor, magma is released. This iron-rich magma magnetizes towards the north & south
pole. As the plates move & spread apart, newer magma is formed, again pointing to the poles, however, since the
other older magma has moved (and still points in it’s original direction) the magnetic rock points in different
directions. (Example above)
c. Hot Spots: places in the mantle close to the crust that are hotter than other regions of the mantle. The heat &
pressure cause the magma to be released, resulting in volcanoes.
(Ex. How the Hawaiian Islands were formed)
III. Plate Boundaries & Movement
a. CONVERGENT PLATE BOUNDARIES: when two plates move into one another
i. Two continental plates collide:
a. results in mountains
ii. Two oceanic plates collide: one moves under the other resulting in:
a. trench forming
b. land or island volcano
Convergent Oceanic-Oceanic
Convergent Oceanic-Continental
Example on Earth:
JAPAN, PHILIPPINES,
ALEUTIAN ISLANDS
Example on Earth:
CASCADE MOUNTAINS,
ANDES MOUNTAINS
b. DIVERGENT PLATE BOUNDARIES:
when two plates move away from one another
i. Two plates move apart: magma comes up & spreads
resulting in ridges (i.e. the Mid-Atlantic Ridge)
Convergent ContinentalContinental
Example on Earth:
HIMALAYAS
c. TRANSFORM FAULT
BOUNDARIES: when two plates
move parallel to one another.
Creates cracks in the crust.
Divergent Oceanic Plates
Divergent Continental Plates
Transform Boundary
Example on Earth:
MID-ATLANTIC RIDGE
Example on Earth:
GREAT RIFT VALLEY
(Africa)
Example on Earth:
SAN ANDREAS FAULT
NOTES: EARTHQUAKES
Earthquakes: The shaking of the earth due to the rapid release of built up
energy in the earth’s crust.
I. Causes of Earthquakes: The Elastic Rebound Theory
a. Slight movement of rocks in/on the earth’s crust
b. Energy builds up over time as the rocks are bent
c. Rocks are bent to their breaking point, releasing energy in
the form of vibrations (earthquake)
d. Rocks return to their original shape
II. Types of Earthquake Waves:
a. Body Waves: travel through the earth’s interior
i. P-Waves (Primary waves): compression waves
1. travel fastest
2. moves through solid, liquid or gas
ii. S-Waves (Secondary waves):
1. move up and down
2. moves through solid only
b. Surface Waves: travel more slowly than body waves. Travel just
below the earth’s surface
i. Rayleigh waves (ground roll): travel like ripples in the water.
ii. Love waves: cause ground shearing
III. Location of an Earthquake:
a. Occurs beneath the earth’s surface (focus)
b. The epicenter is the area on the map where we say that the
earthquake occurs (directly above the focus)
i. Seismographs are placed in many places around the
globe – these are instruments that measure
seismic activity (specifically, waves)
ii. Triangulation: Draw circles around 3 different seismic
centers based on the intensity of the earthquake. Where the
3 circles meet is the epicenter of the earthquake.
c. Reading a seismogram (the readout from the seismograph):
IV. Damage from Earthquakes:
a. Infrastructure damaged (buildings)
b. Liquefaction: water saturates soil, causing it to
move under buildings
c. Tsunamis (massive waves): biggest on record
was the one on Dec. 26, 2006
d. Subsidence (ground sinks) causing landslides
e. Fires due to broken gas lines under cities
NOTES: VOLCANOES
Volcano: an opening or rupture in the earth’s crust that allows molten rock, ash & gas to be released from beneath the
earth’s surface.
TYPES OF VOLCANOES
Drawing
Type
STRATOVOLCANO
CINDER VOLCANO
SHIELD VOLCANO
Description
 Tallest volcanoes
 Forcefull eruptions
 Pyroclastic flow & lava
 Smallest volcanoes
 Non violent eruptions
 lava
 ISLAND BUILDING
volcanoes
 Lava flows slow over
many years.
Example
Mt St. Helens (USA)
Mt Vesuvius (Italy)
Paricutin (Mexico)
Stromboli (Italy)
Kilauea & Mona Loa
(Hawaii)